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Damn noise coming from diff. HELP

O.K. I pulled out my diff. to replace the locking mechanism that you can only get from the dealership and they screwd me on the price of the part as any dealership part would. Anyway I put the bearings back on the diff put the races and the shims in and put the caps over them. Filled it with 3.5 pints of 80w-90. And every time I get on the gas it makes a hum sound. I did not touch the pinion or set any backlash. It wasn't makeing that noise before. Do I have to torque the bolts to a specific torque on the caps that hold the diff, bearings, cap, and shims? Is there a orderd way to tighten those 4 bolts? Any thing you think I did wrong please reply?
84 S-10

Yes, you have to torque the caps but I don't remember the pounds that is take to torque them too. Did you put the shims in the place were they come from. You might have mixed them up when you were doing the bearings and the races. That probably why its humming. The ring gear is too close to the pinion gear. You might try switching the shims. Or you can put a indicator on the ring gear and check the bachlash. What locking piece are you talking about. The pin that screws in the chunk that hold the rod that goes through the spider gears. Is that what you are talking about???

I would not take a chance on your rear end at all. It could cost you a lot in the long run. If its still humming, take it to a shop and have it checked over. The gears should not make any noises at all. The pin you are talking about, can you press it in by hand or do you need a special tool to press it in. The only pin that I know of is the pin that holds the spider gears. Then there is another pin that you put in by hand untill it bottoms out and then you have to screw it the rest of the way in. If the spider gears are worn out, that with make a humming noise too. Replacing spider gears is real easy to do. But on the other hand, if you don't know that much about the physic of the rear end, your better off taking it to a qualified mechanic that specailizes in rear ends. But then again you will never learn how to work on them. Thats how I learned how to work on them. I broke so many in my youth, that I did not have the money to get it fixed, so I had to learn the hard way. Good luck and if you got any more question, just ask, I will be more than happy to help you.:bigthumb:

I switched the shims but now I think I should of changed the races to the other side to. Think that has any thing to do with it? It didn't make any noise before so I know I did something wrong. I don't like taking my truck to the shop to much unless it's a smog. But if it's out of my hands I got no choice. I am a auto student and anything I can learn about vehicles I'm all for it.
Thanks for your help.

The races and the bearing would not make a difference on which side there on. Only the inner and outer bearing are different(wheel bearing virus the differential bearing to my knowledge). Try asking around at your school, someone might be able to take a look at it for you, instead of you having to take it to a mechanic shop. Good luck in auto school. :bigthumb: